package com.hmdp.utils;

import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONUtil;
import com.hmdp.entity.Shop;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.*;

@Slf4j
@Component
public class CacheClient {


    @Resource
    private StringRedisTemplate stringRedisTemplate;


    public void set(String key, Object value, Long time, TimeUnit unit){

        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value),time,unit);
    }

    public void setWithLogicalExpire(String key, Object value, Long time, TimeUnit unit){

        //设置逻辑过期
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }

    public <R,ID> R queryWithPassThrough(String keyPrefix, ID id, Class<R> type,Function<ID,R> dbFallback,Long time, TimeUnit unit){
        String key = keyPrefix + id;

        //1.从redis中查询商铺缓存
        String json = stringRedisTemplate.opsForValue().get(key);
        //2.判断缓存是否命中
        if (StrUtil.isNotBlank(json)){
            //3.命中，直接返回
            return JSONUtil.toBean(json, type);
        }
        //判断命中的是否是空值
        if (json != null){
            //返回一个错误信息
            return null;
        }

        //4.不存在，根据id查询数据库
        R r = dbFallback.apply(id);
        //5.数据库中不存在，返回错误
        if (r == null){
            //直接返回错误信息 会造成 缓存穿透
//            return Result.fail("店铺不存在！");
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
            return null;
        }


        //6.存在，写入redis
        this.set(key,r,time,unit);
        //7.返回
        return r;
    }

}
